Neuropathy is the most common of the secondary complications associated with diabetes, with over half of all patients developing some form of nerve dysfunction in their lifetime. The etiology of diabetic neuropathy is not well understood and animal models of diabetic neuropathy have been widely used to investigate potential etiologic mechanisms. A number of hypotheses have been presented as a result of such studies, including involvement of increased glucose metabolism by aldose reductase, reduced nerve blood flow, oxidative stress and loss of neurotrophic support and it is becoming clear that many of these mechanisms are interconnected. However, conventional drug-based therapies derived from these mechanisms have yet to be validated in clinical trials and there is still no mechanistically targeted, FDA approved, therapy for diabetic neuropathy. There have been recent reports in the clinical literature that local treatment of limbs with near infra red energy (NIRE) can improve symptoms of neuropathy in diabetic patients. The mechanism of action is not clear, although there is a small scientific literature showing that light energy can have a variety of physiologic effects in mammals, including vasodilation and consequent increases in local blood flow. Because the clinical data demonstrating efficacy of NIRE on diabetic neuropathy is limited and further mechanistic studies may be restricted by technical and ethical considerations, we will perform quantitative studies of the efficacy of NIRE in streptozotocin diabetic rats. This animal model exhibits functional disorders of peripheral nerve that resemble early diabetic neuropathy and is useful for screening potential therapeutic approaches for diabetic neuropathy. We will examine the efficacy of NIRE in preventing and reversing structural, functional and neurochemical disorders of peripheral sensory and motor nerves and have already performed a preliminary study that suggests some efficacy is likely to be confirmed. The purpose of the project is to establish (or dispute) the scientific and mechanistic rationale for the use of NIRE in treating diabetic neuropathy: If efficacy is established, our findings will promote future studies designed to identify plausible mechanisms of action.